// 封装链表类
function LinkedList () {
  // 内部的类：节点类
  function Node (data) {
    this.data = data
    this.next = null
  }
  // 属性
  this.head = null
  this.length = 0
  // 1.追加方法
  LinkedList.prototype.append = function (data) {
    // 1.创建新的接点
    var newNode = new Node(data)
    // 2.判断是否添加的是第一个节点
    if (this.length == 0) {
      this.head = newNode
    } else {
      // 找到最后一个接点
      var current = this.head
      while (current.next) {
        current = current.next
      }
      // 最后节点next只想新的节点
      current.next = newNode
    }
    // 3.length++
    this.length += 1
  }
  // 2.toString方法
  LinkedList.prototype.toString = function () {
    // 1.定义变量
    var current = this.head
    var listString = ''
    // 2.循环获取一个个接点
    while (current) {
      listString += current.data + ' '
      current = current.next
    }
    return listString
  }
  // 3.insert方法
  LinkedList.prototype.insert = function (position, data) {
    // 1.对position进行越界判断
    if (position < 0 || position > this.length) return false
    // 2.根据data创建newNode
    var newNode = new Node(data)
    // 3.判断插入的位置是否是第一个
    if (position == 0) {
      newNode.next = this.head
      this.head = newNode
    } else {
      var index = 0
      var current = this.head
      var previous = null
      while (index++ < position) {
        previous = current
        current = current.next
      }
      newNode.next = current
      previous.next = newNode
    }
    this.length += 1
    return true
  }
  // 4.get方法
  LinkedList.prototype.get = function (position) {
    // 1.越界判断
    if (position < 0 || position >= this.length) return null
    // 2.获取对应的data
    var current = this.head
    var index = 0
    while (index < position) {
      current = current.next
    }
    return current.data
  }
  LinkedList.prototype.indexOf = function (data) {
    // 定义变量
    var current = this.head
    var index = 0
    // 开始查找
    while (current) {
      if (current.data == data) {
        return index
      }
      current = current.next
      index++
    }
    // 没有找到，返回-1
    return -1
  }
  LinkedList.prototype.update = function (position, newData) {
    // 越界判断
    if (position < 0 || position >= this.length) return false
    // 查找正确的节点
    var current = this.head
    var index = 0
    while (index++ < position) {
      current = current.next
    }
    // 将position位置的node的data修改为 newData
    current.data = newData
    return true
  }
  LinkedList.prototype.removeAt = function (position) {
    // 越界判断
    if (position < 0 || position >= this.length) return false
    // 判断是否删除的是第一个节点
    if (position == 0) {
      this.head = this.head.next
    } else {
      var index = 0
      var current = this.head
      var previous = null
      while (index++ < position) {
        previous = current
        current = current.next
      }
      previous.next = current.next
    }
    this.length -= 1
    return current.data
  }
  LinkedList.prototype.remove = function (data) {
    // 根据data获取data在列表中的位置
    var position = this.indexOf(data)
    // 根据位置信息，删除节点
    return this.removeAt(position)
  }
  LinkedList.prototype.isEmpty = function () {
    return this.length == 0
  }
  // size()方法
  LinkedList.prototype.size = function () {
    return this.length
  }
}

var list = new LinkedList()
list.append('abc')
list.append('342')
list.append('hhdf')
list.insert(0, 'aaa')
list.insert(3, 'nnn')
console.log(list.get(0))
console.log(list.indexOf('342'))
list.update(2, '111')
console.log(list)
console.log(list.remove('abc'))
